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authorDan Williams <dan.j.williams@intel.com>2011-06-13 17:39:44 -0700
committerDan Williams <dan.j.williams@intel.com>2011-07-03 04:04:51 -0700
commit209fae14fabfd48525e5630bebbbd4ca15090c60 (patch)
treeb251b9b394b3493cc15242ea31002abcb4e9bb59 /drivers/scsi/isci/request.h
parent360b03ed178a4fe3971b0a098d8feeb53333481b (diff)
isci: atomic device lookup and reference counting
We have unsafe references to remote devices that are notified to disappear at lldd_dev_gone. In order to clean this up we need a single canonical source for device lookups and stable references once a lookup succeeds. Towards that end guarantee that domain_device.lldd_dev is NULL as soon as we start the process of stopping a device. Any code path that wants to safely lookup a remote device must do so through task->dev->lldd_dev (isci_lookup_device()). For in-flight references outside of scic_lock we need reference counting to ensure that the device is not recycled before we are done with it. Simplify device back references to just scic_sds_request.target_device which is now the only permissible internal reference that is maintained relative to the reference count. There were two occasions where we wanted new i/o's to be treated as SAS_TASK_UNDELIVERED but where the domain_dev->lldd_dev link is still intact. Introduce a 'gone' flag to prevent i/o while waiting for libsas to take action on the port down event. One 'core' leftover is that we currently call scic_remote_device_destruct() from isci_remote_device_deconstruct() which is called when the 'core' says the device is stopped. It would be more natural for the final put to trigger isci_remote_device_deconstruct() but this implementation is deferred as it requires other changes. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/scsi/isci/request.h')
-rw-r--r--drivers/scsi/isci/request.h7
1 files changed, 2 insertions, 5 deletions
diff --git a/drivers/scsi/isci/request.h b/drivers/scsi/isci/request.h
index 8de2542f081f..9bb7c36257f3 100644
--- a/drivers/scsi/isci/request.h
+++ b/drivers/scsi/isci/request.h
@@ -285,7 +285,6 @@ struct isci_request {
struct isci_tmf *tmf_task_ptr; /* When ttype==tmf_task */
} ttype_ptr;
struct isci_host *isci_host;
- struct isci_remote_device *isci_device;
/* For use in the requests_to_{complete|abort} lists: */
struct list_head completed_node;
/* For use in the reqs_in_process list: */
@@ -681,12 +680,10 @@ static inline void isci_request_free(struct isci_host *isci_host,
struct isci_request *isci_request_alloc_tmf(struct isci_host *ihost,
struct isci_tmf *isci_tmf,
- struct isci_remote_device *idev,
gfp_t gfp_flags);
-int isci_request_execute(struct isci_host *isci_host,
- struct sas_task *task,
- gfp_t gfp_flags);
+int isci_request_execute(struct isci_host *ihost, struct isci_remote_device *idev,
+ struct sas_task *task, gfp_t gfp_flags);
/**
* isci_request_unmap_sgl() - This function unmaps the DMA address of a given